High-Load Borage Oil Nanoemulsion Development via Polyol-Free D‑Phase Emulsification.

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Colloid and Surface Chemistry

Background:

• Nanoemulsions offer enhanced bioavailability for poorly soluble compounds like borage oil.
• Traditional emulsification methods often require complex hydrophilic-lipophilic balance adjustments and organic solvents.
• Developing stable, high-concentration nanoemulsions with minimal surfactant is crucial for pharmaceutical applications.

Purpose of the Study:

• To develop borage oil nanoemulsions using a D-phase emulsification (DPE) method, excluding alkyl polyols.
• To optimize formulation parameters (borage oil, surfactant, initial water concentrations) for desired particle size and stability.
• To assess the physicochemical properties, long-term stability, and in vivo safety of the developed nanoemulsions.

Main Methods:

• Utilized D-phase emulsification (DPE) with polysorbate 80 as the surfactant, achieving high borage oil concentrations (up to 50% w/w).
• Employed a Box-Behnken design to investigate the impact of key formulation variables on nanoemulsion characteristics.
• Characterized formulations using dynamic light scattering, zeta potential measurements, microscopy, X-ray diffraction, and thermal analysis.
• Performed scale-up studies to 1 kg and conducted in vivo toxicity assessments in the Galleria mellonella model.

Main Results:

• Optimized formulations exhibited spherical droplets (300-400 nm) with narrow size distributions (Polydispersity Index < 0.3) and robust zeta potential (<-20 mV).
• Nanoemulsions demonstrated excellent physical stability for up to 12 months under tested conditions.
• Microscopy and diffraction analyses confirmed the amorphous or liquid crystalline state of the borage oil within the nanoemulsions.
• Scale-up to 1 kg maintained comparable physicochemical properties, and in vivo toxicity studies showed no significant adverse effects.

Conclusions:

• The DPE method provides a scalable, solvent-free approach for producing stable, high-concentration borage oil nanoemulsions.
• Initial water concentration was identified as a critical factor in reducing particle size and enhancing stability.
• The developed nanoemulsions exhibit favorable physicochemical properties and safety profiles, suggesting potential for pharmaceutical applications.